Olschwanger Designs. Eric is great, he's really up front on where he does and doesn't make money, and what the process is related to vendors since he's a designer/gemologist rather than a goldsmith. He'll encourage you to find the stone you want and help educate you so you control the budget. He'll import stones so you don't just pick one blind. You'll get to proof a plastic mold so there's no nasty surprise from concept to finished product. Plus in getting quotes for the same design and stone (granted this was 10+ years ago), he came up about 30% cheaper than anywhere else I could find.

Huffman Jewelry in Richardson is solid too. My wife had a pendant commissioned for her dad there. Darryn is full-service, he's normally busy crafting items in the back of the store with his watch guy up front. It's probably a more hands-off process from what I've seen but he's an artist.